NUTRITION LABORATORY. 275 



ADDITIONS TO EQUIPMENT. 



During the war in Europe it has not been possible to receive scientific 

 apparatus from Germany; the Nutrition Laboratory, therefore, in 

 common with numerous other research laboratories, has suffered for the 

 lack of material purchased before the outbreak of hostihties, but, as yet, 

 unobtainable. Several important instruments have been secured in 

 this country, however, and the construction of scientific apparatus by 

 our Laboratory construction staff has been unusually extensive. 



APPARATUS FOR THE PSYCHOLOGICAL LABORATORY. 



A string galvanometer with combination resistance and standardizing 

 outfit, both pieces of apparatus designed by Dr. H. B. Williams, of the 

 Department of Physiology, Columbia University, also an automatic 

 Weule arc lamp, have been installed in the psychological laboratory. 

 This new model of string galvanometer is of great practical advantage 

 to workers in the United States, particularly at the present time, for 

 with the imported instruments the breakage of strings and delay 

 in replacement has been, even in times of peace, most uneconomical. 

 The Wilhams galvanometer supphes an exact physical instrument, 

 inasmuch as equal increments of current will give equal increments of 

 deflection for 8 cm. on either side of the base-line with a magnification of 

 900 diameters. 



An Ives-Cobb visual acuity object has been constructed for us at the 

 Nela Research Laboratory, supplemented by the necessary apparatus, 

 and mounted for use as a testing instrument. 



A pendulum contact-breaker of the general form devised by Lucas 

 has been constructed in the Laboratory shop. The present instru- 

 ment automatically closes the contacts that have been struck open 

 by the rapidly falling pendulum. The interval between the opening 

 of the switches is continuously variable and its duration for any 

 setting is accurately known. The device is used as a stunulus regu- 

 lator v/hen determining the sensory threshold for electrical stimulation. 



RESPIRATION CHAMBERS FOR COLD-BLOODED ANIMALS. 



The researches at the New York Zoological Park necessitated the 

 construction of several respiration chambers of various sizes for 

 experimentation with cold-blooded anmials. As animals of this class 

 have an extraordinarily low metabolism, it was necessary to select the 

 largest ones available for the experiments. Accordingly a chamber was 

 built of sufficient size to contain a Galapagos tortoise weighing 132 kg. 

 Subsequently a recessed cover was designed and employed wliich con- 

 siderably reduced the volume of the chamber and permitted its use for 

 a 16|-foot Indian python and a 7|-foot aUigator. To minimize the 

 attention and labor required in these time-consuming experiments 

 with cold-blooded animals, a valve device was constructed to connect 



